ui: keep detail-page SSE swaps live after the first outerHTML replace

Pipeline fragment payload was a bare <div class=pipeline>, but the
sse-swap=pipeline-N wrapper lived only in the page shell. The first
outerHTML swap destroyed the wrapper, so every subsequent pipeline
event had nothing to target — forcing a manual refresh. RenderPipelineString
now emits the full <section id=pipeline-N sse-swap=... hx-swap=outerHTML>
wrapper, used from both the shell and the orchestrator publish path.

Also drop the red-bar styling from the empty DetailHold placeholder:
the wrapper's detail-hold class was painting an unconditional red band
between Pipeline and Actions whenever no hold was active.

internal/web/templates/pipeline_templ.go

@@ -419,12 +419,87 @@ func Pipeline(nodes []PipelineNode) templ.Component {
 	})
 }
 
+// PipelineSection wraps Pipeline in the same <section id=pipeline-N
+// sse-swap=pipeline-N hx-swap=outerHTML> the runner targets. Used both
+// from the initial detail-page shell and from RenderPipelineString so
+// the wrapper is present on the wire and after every SSE swap — without
+// this, the first outerHTML swap would replace the section with a bare
+// <div class=pipeline>, wiping out the sse-swap attribute and freezing
+// the pipeline until full page reload.
+func PipelineSection(run *model.Run, nodes []PipelineNode) templ.Component {
+	return templruntime.GeneratedTemplate(func(templ_7745c5c3_Input templruntime.GeneratedComponentInput) (templ_7745c5c3_Err error) {
+		templ_7745c5c3_W, ctx := templ_7745c5c3_Input.Writer, templ_7745c5c3_Input.Context
+		if templ_7745c5c3_CtxErr := ctx.Err(); templ_7745c5c3_CtxErr != nil {
+			return templ_7745c5c3_CtxErr
+		}
+		templ_7745c5c3_Buffer, templ_7745c5c3_IsBuffer := templruntime.GetBuffer(templ_7745c5c3_W)
+		if !templ_7745c5c3_IsBuffer {
+			defer func() {
+				templ_7745c5c3_BufErr := templruntime.ReleaseBuffer(templ_7745c5c3_Buffer)
+				if templ_7745c5c3_Err == nil {
+					templ_7745c5c3_Err = templ_7745c5c3_BufErr
+				}
+			}()
+		}
+		ctx = templ.InitializeContext(ctx)
+		templ_7745c5c3_Var11 := templ.GetChildren(ctx)
+		if templ_7745c5c3_Var11 == nil {
+			templ_7745c5c3_Var11 = templ.NopComponent
+		}
+		ctx = templ.ClearChildren(ctx)
+		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 13, "<section id=\"")
+		if templ_7745c5c3_Err != nil {
+			return templ_7745c5c3_Err
+		}
+		var templ_7745c5c3_Var12 string
+		templ_7745c5c3_Var12, templ_7745c5c3_Err = templ.JoinStringErrs(fmt.Sprintf("pipeline-%d", run.ID))
+		if templ_7745c5c3_Err != nil {
+			return templ.Error{Err: templ_7745c5c3_Err, FileName: `internal/web/templates/pipeline.templ`, Line: 292, Col: 41}
+		}
+		_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var12))
+		if templ_7745c5c3_Err != nil {
+			return templ_7745c5c3_Err
+		}
+		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 14, "\" class=\"detail-section\" sse-swap=\"")
+		if templ_7745c5c3_Err != nil {
+			return templ_7745c5c3_Err
+		}
+		var templ_7745c5c3_Var13 string
+		templ_7745c5c3_Var13, templ_7745c5c3_Err = templ.JoinStringErrs(fmt.Sprintf("pipeline-%d", run.ID))
+		if templ_7745c5c3_Err != nil {
+			return templ.Error{Err: templ_7745c5c3_Err, FileName: `internal/web/templates/pipeline.templ`, Line: 294, Col: 47}
+		}
+		_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var13))
+		if templ_7745c5c3_Err != nil {
+			return templ_7745c5c3_Err
+		}
+		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 15, "\" hx-swap=\"outerHTML\"><h2>Pipeline</h2>")
+		if templ_7745c5c3_Err != nil {
+			return templ_7745c5c3_Err
+		}
+		templ_7745c5c3_Err = Pipeline(nodes).Render(ctx, templ_7745c5c3_Buffer)
+		if templ_7745c5c3_Err != nil {
+			return templ_7745c5c3_Err
+		}
+		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 16, "</section>")
+		if templ_7745c5c3_Err != nil {
+			return templ_7745c5c3_Err
+		}
+		return nil
+	})
+}
+
 // RenderPipelineString is the one-shot renderer the orchestrator
 // registers at startup so it can publish pipeline fragments over SSE
-// without pulling in the template package directly.
+// without pulling in the template package directly. Returns the full
+// PipelineSection wrapper so repeat outerHTML swaps preserve the
+// sse-swap target.
 func RenderPipelineString(run *model.Run, stages []model.Stage) string {
+	if run == nil {
+		return ""
+	}
 	var buf bytes.Buffer
-	_ = Pipeline(BuildPipeline(run, stages)).Render(context.Background(), &buf)
+	_ = PipelineSection(run, BuildPipeline(run, stages)).Render(context.Background(), &buf)
 	return buf.String()
 }